Returning to California, there can be no doubt that the hill-like camp places of the Indians in the interior of the country represented a local variation of the shellmounds along the shore. The form and structure of these camping places resemble the shellmounds of the coast. The material differs in part, since the inhabitants of the inland had fewer shells at their disposal. These camping places were inhabited by the Indians quite recently, or are even now inhabited.[[63]] The time when the shellmounds of the Bay shore were vacated by their owners was therefore probably not very long ago. With this view coincides the fact that in the upper strata of the shellmound burial is represented by cremation; a form of burial observed up to the most recent times among the Indians of California. The white immigrants settled first on the seacoast, and it is therefore natural that the aborigines retreated earlier from their shellmounds than their brethren in the interior did from their camp places.
Thus, while the history of the shellmounds of this region probably reaches back more than a thousand years into the past, it must have extended almost to the threshold of modern times. The fact that their roots reached far back into the prehistoric period of California does not prevent our seeing the tops developing almost to the present day.
[56] Powers, l. c., p. 375.
[57] Quoted by Abbott, l. c.
[58] Cf. J. Ranke, Der Mensch, II, p. 536. Those shellmounds are placed in the earlier stone age of the current geologic periods.
[59] l. c., p. 571.
[60] On an average once in every 14 days the high tide reaches a higher mark, which, however, is not considered here.
[61] In a similar manner, Abbott, l. c., p. 449, closes a long general exposition of the reasons which speak either for or against a relatively great age of the shellmounds on the Atlantic coast, with the estimate of an age of at least 1,000 years. His deductions are based upon geological reasons (the sinking of the coast) and the dissimilarities of the cultural remains found in the mounds. Peculiarly enough, D. G. Brinton, reasoning from the analogy of the cultural character of the shellmounds with that of the Indian tribes which the explorers met in this country, thinks he has found an argument against a comparatively high age of the shellmounds. W. H. Dall considers the lower strata of his well-explored Aleutian shellmounds to have an age of about 1,000 years. (Contributions, l. c., p. 53.)
[62] Abbott, l. c., p. 44.